Monitors horizontal and vertical movement across a crack in a corner. The Tell-Tale is hinged enabling it to be used in internal corners of angles between 70 and 180 degrees. Monitors both internal and external corners. Avongard Tell-Tales are precision gauges that consist of two plates which overlap for a part of their length. The bottom plate is calibrated in millimeters and the top plate is transparent and marked with a hairline cursor in the form of a cross. Fix using Screws and Adhesive (not included but available as accessories). Supplied with full instructions and Crack Record Sheet.